To Improve Your Surgical Drilling Skills, Make Use of Your Index Fingers

Abstract

Background: Surgery has greatly benefited from various technologic advancements over the past decades. Surgery remains, however, mostly manual labor performed by well-trained surgeons. Little research has focused on improving osseous drilling techniques. The objective of this study was to compare the accuracy and precision of different orthopaedic drilling techniques involving the use of both index fingers.

Questions/purposes: (1) Does the shooting grip technique and aiming at the contralateral index finger improve accuracy and precision in drilling? (2) Is the effect of drilling technique on accuracy and precision affected by the experience level of the performer?

Methods: This study included 36 participants from two Dutch training hospitals who were subdivided into three groups (N = 12 per group) based on their surgical experience (that is, no experience, residents, and surgeons). The participants had no further experience with drilling outside the hospital nor were there other potential confounding variables that could influence the test outcomes. Participants were instructed to drill toward a target exit point on a synthetic bone model. There were four conditions: (1) clenched grip without aiming; (2) shooting grip without aiming; (3) clenched grip with aiming at the contralateral index finger; and (4) shooting grip aiming at the contralateral index finger. Participants were only used to a clenched grip without aiming in clinical practice. Each participant had to drill five times per technique per test, and the test was repeated after 4 weeks. Accuracy was defined as the systematic error of all measurements and was calculated as the mean of the five distances between the five exit points and the target exit point, whereas precision was defined as the random error of all measurements and calculated as the SD of those five distances. Accuracy and precision were analyzed using mixed-design analyses of variance.

Results: Accuracy was highest when using a clenched grip with aiming at the index finger (mean 4.0 mm, SD 1.1) compared with a clenched grip without aiming (mean 5.0 mm, SD 1.2, p = 0.004) and a shooting grip without aiming (mean 4.9 mm, SD 1.4, p = 0.015). The shooting grip with aiming at the index finger (mean 4.1 mm, SD 1.2) was also more accurate than a clenched grip without aiming (p = 0.006) and a shooting grip without aiming (p = 0.014). Shooting grip with aiming at the opposite index finger (median 2.0 mm, interquartile range [IQR] 1.2) showed the best precision and outperformed a clenched grip without aiming (median 2.9 mm, IQR 1.1, p = 0.016), but was not different than the shooting grip without aiming (median 2.2 mm, IQR 1.4) or the clenched grip with aiming (median 2.4 mm, IQR 1.3). The accuracy of surgeons (mean 4.1 mm, SD 1.1) was higher than the inexperienced group (mean 5.0 mm, SD 1.1, p = 0.012). The same applied for precision (median 2.2 mm, IQR 1.0 versus median 2.8 mm, IQR 1.4, p = 0.008).

Conclusions: A shooting grip combined with aiming toward the index finger of the opposite hand had better accuracy and precision compared with a clenched grip alone. Based on this study, experience does matter, because the orthopaedic surgeons outperformed the less experienced participants. Based on our study, we advise surgeons to aim at the index finger of the opposite hand when possible and to align the ipsilateral index finger to the drill bit.

Level of evidence: Level II, therapeutic study.

Conflict of interest statement

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Figures

Fig. 1 A-D

An overview of all techniques is demonstrated. (A) CG-: the dominant hand holds the drill with four fingers clenched without aligning the ipsilateral index finger (clenched grip). (B) SG-: the dominant hand holds the drill with three fingers clenched, and the index finger is used to help guide the trajectory (shooting grip). (C) CG+: the dominant hand holds the drill with four fingers clenched, and the index finger of the opposite hand is put at the aiming point. (D) SG+: the dominant hand holds the drill with three fingers clenched, and the index finger is used to help guide the trajectory while the index finger of the opposite hand is put at the aiming point.

Fig. 2

The assessment of the distance toward the targeted exit point was measured using a caliper. The distance is marked as “A” (in millimeters). It measures the center of the targeted drilling exit point (black dot in the red circle) to the center of the actual drilling exit point (black plus in the yellow ellipse). To minimize measurement error, the distance for each exit point is measured by taking the sum of the distance between the center of the target and the inner (nearest) border of the drilling hole and the center of the target and the outer (farthest) border of the drilling hole divided by two (A = [B + C]/2). All measurements were in millimeters and all measurements were done by the same researcher (CMER) using the same caliper.

Fig. 3

This is an overview of the results of accuracy in drilling, expressed as the mean distance (mm) between the exit point and the target. Accuracy was defined as the systematic error. CG-: clenched grip without the use of the index finger of the opposite hand; SG-: shooting grip without the use of the index finger of the opposite hand; CG+: clenched grip with the use of the index finger of the opposite hand; SG+: shooting grip with the use of the index finger of the opposite hand. Error bars indicate 1 SD.

Fig. 4

This is an overview of the results of precision in drilling. Data of precision are visualized as a box plot and precision was defined as the random error and expressed as the mean SD of the distances (mm) between the exit points and the target. CG-: clenched grip without the use of the index finger of the opposite hand; SG-: shooting grip without the use of the index finger of the opposite hand; CG+: clenched grip with the use of the index finger of the opposite hand; SG+: shooting grip with the use of the index finger of the opposite hand.